Among thermoplastic resins, liquid-crystalline polymers are known as the materials having excellent dimensional accuracy, damping performance and flowability, and giving very few flash during molding thereof. Owing to these advantageous characteristics, liquid-crystalline polymers have been applied as the materials for various electronics parts in a large quantity.
In particular, with the current requirements for the connectors to have increased heat-resistance (increased productivity by improving the mounting technology), densification (adoption of multi-core structure), and miniaturization, accompanied with ever-increasing performance of electronics devices in recent years, liquid-crystalline polymer compositions which have the above-described characteristics of liquid-crystalline polymers and which are reinforced by glass fibers are adopted as the materials for connectors, (“Total Survey of Engineering Plastics, '92-'93”, pp. 182-194, (1992); and JP-A 9-204951). The design of planar connectors having a grid structure within the outer frame thereof, represented by CPU sockets, shows significant movement of above-described increased heat resistance, densification and miniaturization, and many of the planar connectors adopt glass-fiber reinforced liquid-crystalline polymer compositions.
Even the glass-fiber reinforced liquid-crystalline polymer compositions having good flowability to some degree, however, cannot acquire the performance to satisfy the specification of very thin planar connectors desired in recent years, having 2 mm or smaller contact pitch at the lattice area and having 0.5 mm or smaller thickness of resin portion in the lattice area for holding terminals. For those kinds of planar connector having very thin thickness at the lattice area, filling a resin in the grid section increases the required filling pressure because of insufficient flowability of the resin at the section, thereby raising a problem of increased warp-deformation of the obtained planar connector.
A means to solve the problem is to adopt a liquid-crystalline polymer composition which has good flowability by decreasing the adding amount of glass fibers. That type of composition, however, has insufficient strength, thus raising a problem of deformation generated during reflow in mounting step.
Consequently, there is no planar connector made of liquid-crystalline polymer, having excellent balance of performance characteristics.